Machines for spirally binding sheets of paper on a commercial scale are generally known in the art. For example, U.S. Pat. No. 4,378,822, issued Apr. 5, 1983, discloses driving a spiral coil between a mandrel and a drive wheel. The drive wheel and the mandrel are disposed along one edge of the stack of sheets to be bound. However, the mandrel guides the coil only until the coil actually commences to spirally engage the punched holes of the sheets. Accordingly, a critical difficulty in this type of arrangement is reliably guiding the spiral feed of the coil along the length of the papers and through the punched holes in the sheets.
Another device that has been used to guide the feed of a spiral coil into engagement with prepunched holes in a stack of sheets is a coiling tool, such as is described in U.S. Pat. No. 3,592,242, issued Jul. 15, 1971. The coiling tool includes a mandrel which is surrounded by slotted member. Wire enters the slotted member at one end, is coiled by the mandrel and exits at the opposite end of the tool in the form of a wire which, as it turns feeds successively through the series of punched holes in the sheet stack. While guide members may be disposed along the length of the punched hole edge of the sheets to assist in directing the movement of the spiral wire as it spirally winds through the holes in the sheets, there still exists possibilities for jamming or misthreading due to tension build-up along the spiral wire.
Spiral binding machines of this type are relatively large and generally inappropriate for desktop or office use. U.S. Pat. No. 5,785,479, which is likewise assigned to the assignee of this application, is one attempt to provide a desktop spiral binding machine. The disclosed device, however, is still fairly large and includes a movable cartridge for feeding the spiral coil. Yet another device is disclosed in U.S. Pat. No. 5,584,632 to Stiles et al. The Stiles reference uses a feeding mechanism similar to those described above with regard to the commercial scale machines in that the spiral coil is driven into the punched holes of the sheets by a drive wheel at one end of the paper. Accordingly, a critical difficulty in the disclosed arrangement is reliably guiding the spiral feed of the coil through the punched holes along the entire length of the sheets.